The Rhode Island government signed off on environmental permits for what will become the nation's first offshore wind farm, the project's developer said.

Deepwater Wind received a permit from the Rhode Island Department of Environmental Management to start deployment of its Block Island wind farm slated for the state's waters.

The company's chief executive officer, Jeffrey Grybowski, said the environmental permit is a major step for the development of the planned 30-megawatt wind farm.

"Momentum for the project is strong and we are moving closer to having steel in the water," he said in a statement Thursday.

The U.S. Energy Department this week backed three development projects for offshore wind, though there are no commercial-scale offshore wind farms in service in U.S. territorial waters.

Deepwater Wind says the Block Island wind farm will generate enough power to meet the annual energy demands of more than 17,000 households.

Construction on the transmission system to feed power back to the mainland could begin later this year. Construction on the wind farm itself is slated for 2015.